The Kremlin on Tuesday warned a preliminary decision by Lithuanian lawmakers to lift a constitutional ban on hosting nuclear weapons and the potential deployment of a NATO military base in the country will mark “another significant escalation” of regional tensions.

The comments come shortly after Lithuania’s parliament voted in favor of advancing a constitutional change on deploying nuclear weapons on its territory. It is the first of two ballots required for the change, with the latter scheduled for Jan. 12 next year.

The country, which is a member of both the European Union and NATO and shares a border with Russia’s Kaliningrad exclave on the Baltic Sea, has been looking to remove the constitutional ban to strengthen its resilience amid growing security concerns.

Lithuania has been one of Ukraine’s staunchest allies during Russian President Vladimir Putin‘s more than four-and-a-half year conflict with Kyiv, providing extensive military equipment and financial support.

President Donald Trump, meanwhile, said that he would consider Lithuania’s request for a permanent U.S. military base in the country. “They are friends of mine. They are great people, so we will certainly look at it,” Trump said Monday.

Asked about the developments, Kremlin spokesperson Dmitry Peskov said Tuesday that they “cannot be perceived as anything other than a step toward escalating tensions, just as the deployment of nuclear weapons in a neighboring country cannot,” according to Russian state news agency Tass.

“Neither of these developments will contribute to stability and predictability on the European continent. On the contrary, they will, to our regret, mark yet another significant escalation of tensions. As for Russia, of course, Moscow will be forced to take all necessary measures to guarantee its own security,” Peskov said.